Why Does Weight Depend on Location?

In summary: The "net weight" on a 16 ounce can of peas is 16 ounces regardless. At the equator. At the poles. In Death Valley. On Mount Everest, on the moon and in orbit. That "net weight" is a mass measurement. By law. Exactly as we would want. We would not want to buy and sell goods using a measurement that depends on location.The metric system is based on a fundamental principle: the metre is the length of the path travelled by light in a vacuum over a second, and the second is the time it takes for the light to travel that distance.In summary, the vacuum height of mercury is a measure of how high the pressure in a vacuum is.
  • #1
chito1
1
0
Homework Statement
Vacuum height of mercury
Relevant Equations
Is the pressure in kg / cm2abs when the vacuum height of mercury is 36cmHg?
Is the pressure in kg / cm2abs when the vacuum height of mercury is 36inHg?
Is the pressure in kg / lb/ni2abs when the vacuum height of mercury is 36cmHg?
Is the pressure in kg / lb/ni2abs when the vacuum height of mercury is 36inHg?
Vacuum height of mercury
 
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  • #2
Whaatt?

What's an ni2abs? Can you please define your units, and show the unit conversions that are probably involved? Thanks.
 
  • #3
chito1 said:
Homework Statement:: Vacuum height of mercury
Relevant Equations:: Is the pressure in kg / cm2abs when the vacuum height of mercury is 36cmHg?
Is the pressure in kg / cm2abs when the vacuum height of mercury is 36inHg?
Is the pressure in kg / lb/ni2abs when the vacuum height of mercury is 36cmHg?
Is the pressure in kg / lb/ni2abs when the vacuum height of mercury is 36inHg?

Vacuum height of mercury
I assume ni2abs should be in2absolute.
kg / cm2 is not a pressure. You probably mean kg wt/ cm2. Metric units don't play fast and loose with masses and weights like the American system does.

Regardless of the units used for the height of the mercury, you can use whatever units you like for the pressure. It's just a matter of making the necessary conversions.

If you are asking what units you would use for pressure in order to avoid or minimise conversions, the answer depends on the units you have for the density of mercury. E.g. if that is given as 13.56 grams per cubic centimeter, then a height of y cm of mercury will exert a pressure 13.56y grams wt per sq cm, or 0.01356y kg wt/cm2.

If you have a specific case in mind, please post it.
 
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  • #4
haruspex said:
Metric units don't play fast and loose with masses and weights like the American system does.
Then how come the metrics world quotes weight in kilos whereas the yankee system correctly uses pounds? :))
And no, no one says "I weigh 80 Newtons"!
 
  • #5
rude man said:
Then how come the metrics world quotes weight in kilos whereas the yankee system correctly uses pounds? :))
And no, no one says "I weigh 80 Newtons"!
The "yankee system" is ambiguous about whether pounds means mass or force.

Legally, medically, for purposes of commerce and for purposes of how fat you are when you stand on a scale, pounds are units of mass. Most of the time when we yankees think about the pound, we think of it as a unit of force. One cannot be correct about how a unit is used if one is ambiguous about how that unit is used.

When we say that we "weigh 80 kilograms" that is entirely proper and is a claim about our mass. Even though your physics teacher will ding you for using the word "weight" to denote a mass. Your physics teacher is paid to teach you a jargon usage of the term. That does not preclude the correctness of other meanings.
 
  • #6
jbriggs444 said:
When we say that we "weigh 80 kilograms" that is entirely proper and is a claim about our mass. Even though your physics teacher will ding you for using the word "weight" to denote a mass.
Weight depends on where you are.
If your "weight" is 80kg on Earth it is much less on the Moon. So on the moon your scales give you your incorrect mass. Your scales give you your mass on Earth only. Your "weight" should be denominated in Newtons, not kg.
 
  • #7
rude man said:
Weight depends on where you are.
If your "weight" is 80kg on Earth it is much less on the Moon. So on the moon your scales give you your incorrect mass. Your scales give you your mass on Earth only. Your "weight" should be denominated in Newtons, not kg.
The "net weight" on a 16 ounce can of peas is 16 ounces regardless. At the equator. At the poles. In Death Valley. On Mount Everest, on the moon and in orbit. That "net weight" is a mass measurement. By law. Exactly as we would want. We would not want to buy and sell goods using a measurement that depends on location.

A Toledo scale will give you the same answer for all of those except, possibly, in orbit. "Honest weight, no springs".

A spring scale will also give you the same answer, provided it is valid for commercial use. Such a scale will have been properly calibrated to deliver correct mass measurements in the location where it is used.
 
Last edited:

Related to Why Does Weight Depend on Location?

1. Why does weight vary depending on location?

Weight can vary depending on location due to several factors such as gravity, altitude, and latitude. Gravity is stronger at the poles compared to the equator, which can affect the weight of an object. Altitude can also play a role as objects weigh slightly less at higher altitudes due to a decrease in gravitational pull. Latitude can also affect weight as the Earth's rotation causes a centrifugal force that is stronger at the equator, making objects weigh slightly less.

2. How does gravity affect weight?

Gravity is the force that attracts objects towards the center of the Earth. The strength of gravity can vary depending on location, as it is stronger at the poles compared to the equator. This means that an object will weigh slightly more at the poles compared to the equator. However, the difference is very small and not noticeable in everyday life.

3. Does altitude affect weight?

Yes, altitude can affect weight. As altitude increases, the gravitational pull decreases, making objects weigh slightly less. This is because the Earth's mass is concentrated towards the center, and as you move away from the center, the gravitational force decreases.

4. How does latitude affect weight?

Latitude can affect weight due to the Earth's rotation. The Earth's rotation causes a centrifugal force that is stronger at the equator compared to the poles. This means that objects will weigh slightly less at the equator compared to the poles. However, the difference is very small and not noticeable in everyday life.

5. Can weight vary within the same location?

Yes, weight can vary within the same location. This can be due to differences in altitude, such as standing on top of a mountain versus standing at sea level. It can also be affected by local variations in the Earth's gravitational field, such as near large mountains or underground caves. However, these differences are usually very small and not noticeable in everyday life.

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